S04.891A: Injury of other cranial nerves, right side, initial encounter
S04.891A, injury of other cranial nerves, right side, initial encounter, is listed as a covered diagnosis in 6 Medicare billing and coding articles that apply to 10 HCPCS Level II codes, including G2187 (Patients with clinical indications for imaging of the…), G2188 (Patients with clinical indications for imaging of the…), G2189 (Patients with clinical indications for imaging of the…). The articles come from 5 Medicare contractors. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.
HCPCS Level II codes with S04.891A as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| G2187 | Patients with clinical indications for imaging of the head: head trauma | Carrier judgment | — | 1 |
| G2188 | Patients with clinical indications for imaging of the head: new or change in headache above 50 years of age | Carrier judgment | — | 1 |
| G2189 | Patients with clinical indications for imaging of the head: abnormal neurologic exam | Carrier judgment | — | 1 |
| G2190 | Patients with clinical indications for imaging of the head: headache radiating to the neck | Carrier judgment | — | 1 |
| G2191 | Patients with clinical indications for imaging of the head: positional headaches | Carrier judgment | — | 1 |
| G2192 | Patients with clinical indications for imaging of the head: temporal headaches in patients over 55 years of age | Carrier judgment | — | 1 |
| G2193 | Patients with clinical indications for imaging of the head: new onset headache in pre-school children or younger (<6 years of age) | Carrier judgment | — | 1 |
| G2194 | Patients with clinical indications for imaging of the head: new onset headache in pediatric patients with disabilities for which headache is a concern as inferred from behavior | Carrier judgment | — | 1 |
| G2195 | Patients with clinical indications for imaging of the head: occipital headache in children | Carrier judgment | — | 1 |
| G0255 | Current perception threshold/sensory nerve conduction test, (snct) per limb, any nerve | Non-covered by Medicare | Not covered | 5 |
Medicare policy articles listing S04.891A
- A57307: Billing and Coding: Nerve Conduction Studies and Electromyography (CGS Administrators, LLC (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A57478: Billing and Coding: Nerve Conduction Studies and Electromyography (WPS Insurance Corporation (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A54969: Billing and Coding: Nerve Conduction Studies and Electromyography (Noridian Healthcare Solutions, LLC (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A57668: Billing and Coding: Nerve Conduction Studies and Electromyography (Wellpoint Federal (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A56619: Billing and Coding: Nerve Conduction Studies and Electromyography (Palmetto GBA (MAC - Part A, MAC - Part B); 1 Level II codes). LCD with the same title: L34594, L34859, L35048, L35081
- A56612: Billing and Coding: CT of the Head (Palmetto GBA (MAC - Part A, MAC - Part B); 9 Level II codes). LCD with the same title: L34417
A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.
Other S04 diagnoses (Injury of cranial nerve)
- S04.892A — Injury of other cranial nerves, left side, initial encounter
- S04.811A — Injury of olfactory [1st ] nerve, right side, initial encounter
- S04.812A — Injury of olfactory [1st ] nerve, left side, initial encounter
- S04.51XA — Injury of facial nerve, right side, initial encounter
- S04.52XA — Injury of facial nerve, left side, initial encounter
Frequently asked questions
Does Medicare cover S04.891A (Injury of other cranial nerves, right side, initial…)?
Medicare covers items and services, not diagnoses. 6 Medicare billing and coding articles list S04.891A as a covered diagnosis for 10 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.
Which HCPCS codes can be billed with ICD-10 S04.891A?
The Level II codes from the policies most specific to this diagnosis are G2187 (Patients with clinical indications for imaging of the…, 1 article); G2188 (Patients with clinical indications for imaging of the…, 1 article); G2189 (Patients with clinical indications for imaging of the…, 1 article); G2190 (Patients with clinical indications for imaging of the…, 1 article); G2191 (Patients with clinical indications for imaging of the…, 1 article). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list S04.891A?
A57307 (Billing and Coding: Nerve Conduction Studies and Electromyography); A57478 (Billing and Coding: Nerve Conduction Studies and Electromyography); A54969 (Billing and Coding: Nerve Conduction Studies and Electromyography), and 3 more articles.
What is ICD-10-CM code S04.891A?
S04.891A is the ICD-10-CM code for injury of other cranial nerves, right side, initial encounter, in category S04 (Injury of cranial nerve), chapter 19: Injury, poisoning and other consequences of external causes.
Next steps
- Run a reimbursement report for a device billed under G2187
- Watch G2187 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for G2187
Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.
Chapter 19: Injury, poisoning and other consequences of external causes · All diagnoses · HCPCS lookup